Enter the range of values for x:
B
15
2x - 10
С
48°
A
18
[?]
Enter

=========================================
Explanation:
Since AB is smaller than AD, this must mean the angle ACB is smaller than angle ACD. Note how these angles are opposite the sides mentioned.
So 2x-10 < 48
At the same time, 2x-10 is also larger than 0.
Overall, we can say 0 < 2x-10 < 48
---------
Let's solve for x
0 < 2x-10 < 48
0+10 < 2x < 48+10 ...... add 10 to all sides
10 < 2x < 58
10/2 < x < 58/2 ..... divide all sides by 2
5 < x < 29